This invention relates to apparatus for testing a liquid sample by immersion therein of a probe for coaction therebetween. The said coaction may be of a chemical or of a physical nature.
Certain chemicals can be adsorbed or covalently bonded to a plastics substance such as polystyrene, and yet be able to enter into other chemical reactions. An example of such a chemical is the globulin fraction of antiserum against alpha-feto protein. In this particular example the fact is used for the determination of the concentration of alpha-feto protein in human blood serum. The chemical and the plastics material onto which it is to be adsorbed, or covalently bonded, have been brought into contact with one another manually, either by immersing a plastics solid form in a solution of the chemical; or by plastics-coating the inside of a tube-like container. The coated plastics form, or coated container, may then be used to determine the concentration of an analyte in a liquid sample by dipping or by filling. Each stage of such an analysis has required a manual transfer which is time consuming, imprecise, causes problems in maintaining patient identity, and is expensive. The present invention allows these disadvantages to be reduced through a partial mechanisation of the process. It is to be understood that the invention is not restricted in use to the chemical testing of samples, but may also be applied to physical tests.
According to the invention, apparatus for testing at least one liquid sample, by immersion therein of a probe for coaction between said probe and sample, has a reloadable sample carrier for at least one sample container; a reloadable probe carrier for at least one probe; a frame having locating means for relatively locating the sample carrier and the probe carrier laterally in the frame, parallel motion means for guiding the probe longitudinally into the sample container and stop means for locating the probe at a predetermined distance into the sample container, locking means preventing the probe from being withdrawn more than a predetermined distance in the outward direction from the sample container, timing and control means for releasing said locking means after a predetermined time, and self acting withdrawal means for withdrawing the probe and probe carrier to a position clear of the sample container; the said sample carrier and probe carrier being arranged so as to be severally removable away from the said frame.
The apparatus may be arranged for a plurality of probes and samples for coaction simultaneously.
The stop means and locking means may include an electromagnet and an armature therefor; and the timing and control means are conveniently actuated through switch means by longitudinal relative movement of the probe carrier and sample carrier.
The self-acting withdrawal means conveniently includes a spring, aiding withdrawal; and preferably also includes damper means, which may be an air dash pot.
The sample carrier may be arranged to be heatable electrically and thermostatically by a heating element and temperature sensitive element therein; and the heating element may be arranged to be connectable to an energy source only when the sample carrier is put into the frame so it can register with a probe carrier.
The probe carrier is preferably formed so it can be placed on a flat surface without any probe being dislodged from it and so that the probe does not touch the surface.
Oscillating means may be included in the apparatus which can oscillate the probe carrier longitudinally through a small distance in relation to the sample carrier whereby a probe may be moved in an oscillatory manner in relation to a sample in a sample container.
The apparatus may be arranged so that the frame has a plurality of locations, each for a set of probe carrier and sample carrier, which are then preferably formed each with characteristic mutually associable portions, whereby a given one of the plurality of locations in the frame can be occupied only by an individual probe carrier and an individual corresponding sample carrier. In one embodiment the associable portions are interlocking portions interlocking through direct translatory movement between frame and probe carrier and between frame and sample carrier.